Processing color photographic materials



United States Patent 3,140,177 PROCESSING COLOR PHOTOGRAPHIC MATERIALSMaurice E. Welch, Brockport, N.Y., assignor to Eastman Kodak Company,Rochester, N.Y., a corporation of New Jersey No Drawing. Filed Nov. 10,1960, Ser. No. 68,359

9 Claims. (Cl. 9656) This invention relates to color photography andparticularly to a method for emulsion hardening and prevention ofmagenta-fading in color photographic materials.

In processes of photographic color development, it is frequentlydesirable to use a formaldehyde hardening bath for purposes of hardeningthe emulsion layers. As is well known, formaldehyde will act as anemulsion layer hardener when used in a treating bath of alkaline pH.

In processes of color development, there frequently results theformation of stain in the white image areas or fading in which the dyein the image areas becomes decolorized. In either case the problem mayresult from unused dye-forming coupler remaining in the emulsion layerafter processing. Particularly subject to this difliculty has been themagenta-dye-forming emulsion layer resulting from unused magenta couplerremaining in the layer after processing.

It has now been found that by the use of a particular acid-aldehyde bathas a final treating bath, each of the aforementioned difiiculties can beovercome which at the same time has the end function of hardening theemulsion layer. It was very unexpected to find that polycarboxylicacid-formaldehyde solutions Would harden the emulsion layer since it iswell known that formaldehyde to be effective as a hardener must bepresent in an alkaline solution. While it is true that formaldehyde mustbe in an alkaline solution to impart hardness while wet, I discoveredthat polycarboxylic acid-formaldehyde solutions would impart hardness tothe emulsion layer, while at the same time preventing magenta stain andfading, if the emulsion layer was dried in the presence of theacidaldehyde treating solution. Clearly, therefore, my inventioncomprises a specialized procedure for color photo-' graphic developmentemploying a polycarboxylic acidaldehyde treating bath.

The processes of photographic color development to which my inventionpertains relates to processes which produce dyed images in emulsionlayers where the colorforming couplers are incorporated directly in suchlayers. Processes of this type have been described in Fischer US. Patent1,055,155, granted March 4, 1913.

It is an object of the present invention to provide a process wherebymagenta-fading can be prevented in color coupler incorporated multilayerphotographic materials. Another object is to provide a process wherebythe emulsion layers can be hardened in the single step which alsoprevents magenta-fading. A further object is to provide a treating bathwhich can be employed in a process of this invention to accomplish theobjects herein stated.

These objects are accomplished by a special procedure for processing ofcolor coupler incorporated multilayer photographic materials, whichemploys as a final treatment at treating bath comprising a water-solublepolycarboxylic acid and an aliphatic aldehyde selected from the groupconsisting of formaldehyde, paraformaldehyde, and acetaldehyde. Thewater-soluble polycarboxylic acids which can be employed in thisinvention comprise polycarboxylic acids having from 2 to 6 carbon atoms.Suitable acids comprise oxalic, malonic, malic, tartaric, citric,succinic, glutaric and adipic. According to the invention thephotographic material being processed is treated for a short time in abath of the above composition after which the photographic material isdried with 3,140,177 Patented July 7, 1964 "ice no further treatment.The time of treatment with the treating bath can vary widely but fromabout 15 seconds to about 30 seconds is adequate. Drying of the materialafter treatment can be in any conventional manner.

The polycarboxylic acid-aldehyde treating bath of my invention can beused as the final treating bath after conventional color processingprocedures. The bath does not form an insoluble complex and is notprecipitated by reaction with residual developing agents, fixers, etc.,which may be retained by the film or in the layers thereof. Likewise, nodifliculty has been encountered with the operativeness of the processingequipment through the use of the bath. The bath is not unusuallycorrosive and sludge or other undesirable developments have not occurredwhere the present baths have been employed.

The colored photographic materials treated according to the inventioncomprise color materials Where the couplers are incorporated in thesensitive emulsion layers. According to one embodiment of thisinvention, multilayer emulsion layers containing color formers orcouplers, such as those described in US. Patent 2,322,027, issued June15, 1943, are developed for approximately 2 minutes and 15 seconds in adeveloper of the following composition:

Water ml 800 Benzyl alcohol ml 12.0 Calgon g 2.0

Sodium sulfite g 2.0 Sodium carbonate g 22.0 Sodium bicarbonate g 2.75Sodium bromide g 0.4 Sodium chloride 0.59

4 amino N-ethyl-N-(methanesulfonamidoethyl)- m-toluidinesesquisulfatemonohydrate g 4.0 Water to make 1 liter.

After development, the print material is washed for about 5 seconds witha fine spray and shortstopped in an acid stop bath, such as Water ml 800Acetic acid (glacial) ml 8.6 Water to make 1 liter.

The print material is then bleached in a ferricyanide bleach, such asfollows:

Water ml 800 Borax g 1 Sodium ferrocyanide, decahydrate g 25.7 Potassiumpersulfate g 6.1 Sodium bromide g 4.75 Boric acid g 13.3 Sodium nitrateg 30.0

Water to make 1 liter.

After a short rinse, the color print material is then fixed in a hypofixing bath, such as Water ml 800 Sodium thiosulfate g Sodium sulfite g15 Acetic acid (glacial) ml 12 Zinc sulfate monohydrate g 8 Borax g 3.1

EXAMPLE 1 Borax g 20.8 Citric acid g 36.6 Formaldehyde ml 3.75 Water tomake 1 liter. Final pH of the bath was pH 3.5.

EXAMPLE 2 Sodium metaborate g 18 Citric acid g 30 Formalin (37.5 percentformaldehyde) ml 10 Water to 1 liter. Final pH of the bath was pH 3.6.

EXAMPLE 3 Borax g 20.8 Tartaric acid g 18.1 Formaldehyde ml 5.0 Water to1 liter. Final pH of the bath was pH 3.5.

EXAMPLE 4 Borax g 4.3 Succinic acid g 20.0 Formalin (37.5 percentformaldehyde) ml 15.0 Water to 1 liter. Final pH of the bath was pH 3.5.

EXAMPLE 5 Borax g 5.1 Succinic acid g 20.0 Acetaldehyde g 22.0

Water to 1 liter. Final pH of the bath was pH 3.5.

After a short rinse in any one of the final treating baths of the abovecompositions and after drying with no further treatment, there wasobtained a multicolor print containing stain-free, positive dye imagesof excellent brilliance and freedom from color degradation. The printsproduced by the novel procedure of this invention resulted in multicolorprints which were not subject to magenta dye-fading in the image areas.The prints were also stable against the formation of a yellow stain inthe high light or white areas of the prints.

Where the final treating bath of my invention was used according to theprocedure herein described, the processed prints were stable againstmagenta-fading throughout a ten-day test period in a dry oven at 140 F.and 20 percent relative humidity, whereas comparable prints processed ina conventional manner lost 0.2 density unit in a magenta patch having agreen density of 1.0.

In the polycarboxylic acid-aldehyde treating baths of my invention, thepH of the bath for optimum results can advantageously be within therange of about pH 3.0 to about pH 4.0. The most useful range is fromabout pH 3.3 to about pH 3.7. In preparing the bath, a compound whichhas a buffering action with the polycarboxylic acid is normally used;one such buffering compound is borax. The useful range of concentrationfor the polycarboxylic acid can vary widely. Ordinarily thepolycarboxylic acid compound is added in the treating bath in the amountfrom about 0.5 percent to about 15.0 percent. Where the higher amountsof polycarboxylic acid are used, as is apparent, a correspondinglygreater amount of a buffering compound would be needed to give desiredpH.

An aldehyde of this invention can be added to the treating bath in anamount which can vary over a wide range. A useful concentration in thebath is from about 0.1 percent to about percent, with the most usefulconcentration in the range from about 1 percent to about 4 percent.

The treating bath, when used as a final bath in the Processing sequence,produces (1) an improved magenta dye stability and (2) hardening of thegelatino-emulsion layer. Improved dye stability is thought to occur inthat the bath functions to tie up unused coupler so that it does notreact with magneta dye to produce a colorless product. Particularly inlow density areas, large amounts of unused coupler remain since only asmall amount of coupler has been used to form the magenta dye image. Thecolorless effect produced is commonly referred to as fading and morespecifically as pink toe fade.

The hardening effect which is obtained according to the presentinvention can be obtained in photographic materials other than thosewhich are subject to magenta fading as indicated above. It will beapparent that the hardening effect obtained through the use of thetreating baths of this invention, when used as a final treatment, can beobtained in any of the gelatino-type photographic emulsions.

Color print materials prepared according to the disclosure in US. Patent1,055,155, referred to above, which had been processed according to theprocedure of this invention and which employed the final treating bath,Were checked for degree of hardness imparted by the invention. To makethis determination, three strips of the processed print material wereplaced in a beaker of water at room temperature. The temperature of theWater was then raised to boiling, which took about 35 minutes, and thencontinued at boiling for a total time of about 65 minutes. The resultsof the determination are given in the following example.

EXAMPLE 6 The three strips of processed color material were given afinal treatment in a treating bath having a composition as given below.After final treatment, each strip Strip 111w} formalin in final treating35 minutes. 35 minutes.

a 1. Strip 210 ml. formalin per liter in 40 minutes...

42 minutes. final treating bath. Strip 3-i0 ml. formalin per liter inNone after 60 None after 60 final treating bath. minutes. minutes.

The results of this example show that a degree of hardness is impartedto the emulsion layers where the polycarboxylic acid-aldehyde final bathis employed without subsequent washing.

In accordance with the present invention, the magenta dye step imagesare produced by color-developing silver halide emulsions containingmagenta color formers with a suitable aromatic primary arnino colordeveloping agent. Suitable developing agents comprise 4-aminoaniline, 4-ethylaminoaniline, Z-diethylaminoaniline, 4-dialkylarninoaniline, e.g.,4-dimethylaminoaniline, 4-diethylaminoaniline, 4- [N- (B-hydroxyethyl-N-ethyl] -aminoaniline, 4- amino N ethyl N (Bmethanesulfonamidoethyl)-2- methylaniline sulfate, and the like. Thesedeveloping agents are preferably used in the form of their salts, suchas the hydrochloride or hydrosulfate, since in this form they are moresoluble and stable than the free bases. Other suitable color developershave been described in US. Patents 2,213,986, issued September 10, 1940,and 2,902,366, issued September 1, 1959. The oxidation products of anyof these aromatic primary amino developing agents couple with thepyrazolone color former to form a magenta dye image of the azomethinetype in the emulsion. After removal of the silver image by bleaching andfixing in a manner well known in the art, the

color image remains in the emulsion and it is to the preservation ofthis magenta image to which the present invention pertains.

A procedure for the process of forming colored images in photographiccolor materials is fully described in U.S. Patent 2,486,440, issuedNovember 1, 1949.

Typical couplers, which form the magenta image in multicolorphotographic materials, are pyrazolone compounds. Examples of suchpyrazolone compounds are the following:

1-phenyl-3- (4'-a-sulfostearamido) -phenoxyacetamido- 5 -pyrazolone1-phenyl-3- (4'-u-sulfostearamido) -phenylacetamido- 5 -pyrazolonel-phenyl-3- (4-a-sulfostearamido) -benzamido-5- pyrazolone 1-phenyl-3- 3'-a-sulfostearamido) -benzamido-5- pyrazolone 1-phenyl-3-methyl-4-paradimethylaminob enzal-S pyrazolonel-phenyl-3-methyl-4-phenylmethylmethylene-S- pyrazolone 1-phenyl-3-methyl-4-phenylethylidene-S-pyrazolone1-phenyl-3-methyl-4-m-nitrophenylmethylmethylene- 5 -pyrazolone 3-N-acetylaniline-5 -pyrazolone l-phenyl-3 -hydroxy-5-phenyliminopyrazolone The pyrazolone compounds indicated herein can beprepared according to the disclosures of US. Patents 2,213,986;2,902,366; and 2,311,081 and 2,311,082, issued February 16, 1943.

The present development process can be employed for the production ofcolored photographic images in layers of gelatin which are supported bya transparent medium such as glass, a cellulose ester, or an opaquereflecting medium such as paper. The emulsion can be coated as a singlelayer on the support or as superimposed layers on one or both sides ofthe support.

The invention has been described in detail with particular reference topreferred embodiments thereof but it will be understood that variationsand modifications can be effected within the spirit and scope of theinvention as described hereinabove and as defined in the appendedclaims.

I claim:

1. In the preparation of a finished multicolor photographic elementcontaining in a gelatin substrate a magenta image and a substantialamount of residual pyrazolone photographic color coupler capable ofcoupling with the oxidation products of an aromatic amino photographiccolor developer to form a magenta image, the process which comprisestreating as a final processing step said photographic element with anaqueous treating bath comprising (1) 0.1% to of an aldehyde selectedfrom the class consisting of formaldehyde and acetaldehyde, and

(2) 0.5% to 15% of a water-soluble polycarboxylic acid having 2 to 6carbon atoms,

said treating bath having a pH of about 3 to 4, and thereby hardeningsaid gelatin and reducing fading of said magenta image.

2. The process of claim 1 wherein the treating bath comprises a solutionof formaldehyde and a water-soluble polycarboxylic acid containing from2 to 16 carbon atoms.

3. The process of claim 1 wherein the treating bath comprises a solutionof formaldehyde and citric acid.

4. The process of claim 1 wherein the treating bath comprises a solutionof formaldehyde and tartaric acid.

5. The process of claim 1 wherein the treating bath comprises a solutionof formaldehyde and succinic acid.

6. The process of claim 1 wherein the treating bath comprises a solutionof acetaldehyde and succinic acid.

7. The process of claim 1 wherein the treating bath comprises a solutionof formaldehyde and adipic acid.

8. In the preparation of a finished multicolor photographic elementcontaining in a gelatin substrate a magenta image and a substantialamount of residual pyrazolone photographic color coupler capable ofcoupling with the oxidation products of an aromatic amino photographiccolor developer to form a magenta image, the process which comprisestreating as a final processing step said photographic element with anaqueous treating bath comprising (1) 1% to 4% of an aldehyde selectedfrom the class consisting of formaldehyde and acetaldehyde, and

(2) 0.5% to 15% of a water-soluble polycarboxylic acid selected from theclass consisting of citric acid, tartaric acid, succinic acid, andadipic acid,

said treating bath having a pH of about 3 to 4, and thereby hardeningsaid gelatin and reducing fading of said magenta image.

9. The process of claim 8 wherein borax is used in the treating bath asa buffer to maintain the pH of the treating bath at a pH of 3 to 4.

References Cited in the file of this patent UNITED STATES PATENTS2,518,686 Harsh et al Aug. 15, 1950 2,579,435 Mackey Dec. 18, 19512,579,436 Mackey Dec. 18, 1951 2,657,139 Bates Oct. 27, 1953 2,788,274Ranger Apr. 9, 1957 2,913,338 Bates et al. Nov. 17, 1959 3,095,302Jeffreys et al. June 25, 1963 OTHER REFERENCES Royals: Advanced OrganicChemistry, Prentice-Hall, N.J., January 1956, page 780 relied upon.

1. IN THE PREPARATION OF A FINISHED MULTICOLOR PHOTOGRAPHIC ELEMENTCONTAINING IN A GELATIN SUBSTRATE A MAGENTA IMAGE AND A SUBSTNATIALAMOUNT OF RESIDUAL PYRAZOLONE PHOTGRAPHIC COLOR COUPLER CAPABLE OFCOUPLING WITH THE OXIDATION PRODUCTS OF AN AROMATIC AMINO PHOTOGRAPHICCOLOR DEVELOPER TO FORM A MAGENTA IMAGE, THE PROCESS WHICH COMPRISESTREATING AS A FINAL PROCESSING STEP SAID PHOTOGRAPHIC ELEMENT WITH ANAQUEOUS TREATING BATH COMPRISING (1) 0.1% TO 10% OF AN ALDEHYDE SELECTEDFROM THE CLASS CONSISTING OF FORMALDEHYDE AND ACETALDEHYDE, AND (2) 0.5%TO 15% OF A WATER-SOLUBLE POLYCARBOXYLIC ACID HAVING 2 TO 6 CARBONATOMS, SAID TREATING BATH HAVING A PH OF ABOUT 3 TO 4, AND THEREBYHARDENING SAID GELATIN AND REDUCING FADING OF SAID MAGENTA IMAGE.